So at exactly 3:00 a.m. the wife and I are sound asleep when I am awoken by a subtile crash in the basement below. I laugh at what I presumed was our 15lb cat chasing bugs/mice/gremlins, until I felt him at our feet on the bed. In a split second I was up with my XD9 in hand, creeping towards the door. With senses at full alert, zero-to-adrenaline rush, my wife giving me the WTH, I ease around into the hall. There, a lone figure in the dark stood in the middle of the hallway some five yards away. I came about >this< close to wasting our vacuum cleaner.
Upon further lecturing, the wife will remember to put the vacuum cleaner up before bed when she's done with it, unless she wants to have to buy another.
ETA: Oh - and the crash was a board that had fallen over where I'd misaligned it on the basement wall.